Hi,
In the light of my destroying the issue sandbox and of some recent
discussion on the working group and elsewhere, I feel that the issues of
OWL and SKOS coexistence is still not completely rendered in the
existing issues, and would like to discuss it in one of the next teleconf.
The current issue regarding OWL-DL and SKOS, named
"CompatibilityWithOWL-DL" [1] reads: "What are best practices for using
the SKOS vocabulary within the constraints
required for OWL-DL compatibility?". To me, the main question behind
that was "can the SKOS model be encoded as an OWL-DL ontology?", which
is the way it is more-or-less put in the corresponding requirement from
the use case draft [2]
Yet there is another problem, which is the use of SKOS in ontologies
(OWL or simple RDFS) so as to define ontology classes (or instances of
classes) by means of SKOS features.
This could be the case for example if for whatever purposes (ontology
population from texts for example) an ontology designer wants to use
more types of labels than what the single rdfs:label allows for standard
ontologies. Or to insert existing owl:Class (e.g. exOnt:Planet) and
instances (exOnt:Venus) into a thesaurus-like thematic structure
(exOntVenus skos:broader exOntPlanet, exOnt:Planet skos:broader
exTh:Astronomy), which could be very useful to develop browsers more
useful for humans.
I presented SKOS to a biomedical workshop this week, and it seems that
some people had the wish to use SKOS, but on 'real' ontologies they were
developing. And my discussion with Daniel also made me think this was
what he had in mind (but now I'm really not sure) when he said:
"There are certainly communities who need to describe things, names of
things, and both (in the case of RadLex). Ideally, SKOS should be able
to be useful to these communities" [3]
To put things clearly right now: I don't think this is a absolute
requirement for SKOS, and indeed it could be dangerous to treat it in
this working group, because it is difficult and it could make the whole
picture of using SKOS fuzzier and tangled with ontology design
considerations.
However I think it is important to acknowledge the issue, because I
think it is important (if just to enable people to make one big,
definitive and exclusive choice between OWL and SKOS). Just trying to
hide the corpse in the cupboard would not be really professional, I
guess ;-)
Additionally, the resolution of such an issue might in the end just
require writing some guidelines. Saying for example that it is legal to
use SKOS features to define ontology classes from a SKOS perspective,
giving some example, but warning that the process may cause the
resulting ontology to be OWL-Full, because OWL classes could be inferred
to be instances of the class skos:Concept because of some statements [4].
What do you think of it?
Cheers,
Antoine
[1] http://www.w3.org/2006/07/SWD/track/issues/38
[2]
http://www.w3.org/TR/2007/WD-skos-ucr-20070516/#R-CompatibilityWithOWL-DL
[3] http://lists.w3.org/Archives/Public/public-swd-wg/2007May/0075.html
[4] http://lists.w3.org/Archives/Public/public-swd-wg/2007Jun/0021.html